1. Technical Field
The present invention relates to a semiconductor wafer, a test substrate and a test system. The preset invention relates to, in particular, a semiconductor wafer in which a plurality of semiconductor circuits are formed, a substrate for testing the plurality of semiconductor circuits formed on the semiconductor wafer, and a test system thereof.
2. Related Art
In testing of measurement circuits such as semiconductor circuits, to judge pass/fail of the measurement circuits, measurements of signals output by the measurement circuits are conducted. For example, a test apparatus judges pass/fail of a measurement circuit based on characteristics of a signal output by the measurement circuit, such that the output signal has a predetermined logical pattern, a certain electrical property and so forth.
A test module in which test circuits are fabricated is typically coupled to measurement circuits through cables, connectors, a substrate and so forth, as described, for example, in WO2004/090561. Therefore, the test apparatus needs an element provided thereof, that has a driving capability corresponding to parasitic capacitance caused by the cable, the connector, the substrate and so forth, in order to measure signals accurately. For example, the test apparatus can measure a signal output by a driver which is disposed at an output end of a measurement circuit, with a relatively high accuracy. However, signals at nodes inside the measurement circuit cannot be accurately measured.
To address such problem, test circuits may be disposed close to the measurement circuits so that a signal transmission distance between the measurement circuits and the test circuits can be shortened. In addition, internal nodes in a measurement circuit may be connected to measurement terminals thereby signals at the internal nodes in the measurement circuit can be accurately measured. Such measurement terminal may be provided so as to correspond to each internal node that is to be measured, and signals at various nodes in the measurement circuit can be measured.
The measurement terminals facilitate an electrical connection with an external measuring device. However, they occupy a substantial area. Therefore, it is not preferable to provide a large number of the measurement terminals in the measurement circuit, which could reduce an area where actual operation circuits are to be formed.